1. Field of the Invention
The present invention relates to a physical property measuring method for a thin-film transistor liquid crystal panel, and a physical property measuring apparatus for a thin-film transistor liquid crystal panel.
2. Description of the Related Art
In regard to a thin-film transistor (TFT) liquid crystal panel, measuring various physical properties of a liquid crystal layer of the TFT liquid crystal panel has heretofore been difficult because of its circuit configuration. Therefore, ion density measurement for ions as impurities included in a liquid crystal layer or measurement of various physical properties such as a voltage holding ratio is usually substituted by material evaluation using a test liquid crystal cell having no TFT which is manufactured separately from an actual product (a TFT liquid crystal panel) having a TFT.
However, measurements of various physical properties of the test liquid crystal cell are of course different from various physical properties of the TFT liquid crystal panel that is the actual product. Further, an additional cost to fabricate the test liquid crystal cell separately from the actual product is required. Furthermore, since the various physical properties of the actual product cannot be measured, various physical properties of a defective product that can be produced among the actual products cannot be of course measured.
Under such circumstances, for example, JP-A 2001-264805 (KOKAI) discloses the following technology as a technology that is used to measure a voltage holding ratio of a TFT liquid crystal panel.
That is, according to the technology disclosed in JP-A 2001-264805, a change in transmitted light intensity of a liquid crystal panel with time is measured at the time of driving a TFT, a voltage-transmittance characteristic curve is used to covert the measured transmitted light intensity into a voltage, and an attenuation value of the voltage involved by the change in transmitted light intensity with time is acquired, thereby obtaining a voltage holding ratio of the TFT liquid crystal panel.
However, since a voltage holding ratio measuring method for a TFT liquid crystal panel disclosed in JP-A 2001-264805 is a measuring method using an optical technique, its accuracy is of course inferior to that of a measuring method using an electrical technique.
Meanwhile, in a TFT liquid crystal panel, a defective region which is called an inlet port stain among persons skilled in the art is irregularly produced near a liquid crystal inlet port of the TFT liquid crystal panel in a manufacturing process thereof. Therefore, a technology that enables measuring physical properties of a liquid crystal layer alone in a desired region (pixel) of the TFT liquid crystal panel is demanded. According to such a technology, not only the inlet port stain generating region but also a region concerning, e.g., a failure of the TFT liquid crystal panel can be found.
However, the technology that enables measuring physical properties of the liquid crystal layer in a desired region (pixel) of the TFT liquid crystal panel is not suggested, and the technology disclosed in JP-A 2001-264805 is not of course such a technology.